During RNA silencing, RNAs of about 21 to 24 nucleotides in length are generated, which are incorporated into a protein complex where they serve as guide RNAs to direct the down-regulation of gene expression at the transcriptional or posttranscriptional level. These small silencing RNAs are called “siRNAs” or “microRNAs”, depending upon their biogenesis: endogenous siRNAs derive from long double-stranded RNA and miRNAs derive from local hairpin structures within longer transcripts. RNA silencing occurs in plants, and a better understanding of this process would be useful. In addition, new compositions (e.g., nucleic acid constructs) and methods of achieving RNA-based silencing would be useful, and plants in which expression of one or more genes of interest is modulated, e.g., inhibited, would be of great use.